The present invention relates to an assembly system for mounting and interconnecting plug-in circuit boards (also referred to as plug-in modules) as used in electrical communications devices. Such an assembly system is disclosed in German Utility Model Pat. No. 72/5,350. It is composed of plug-in modules carrying electrical components and, along one edge, multipoint connectors. A plurality of plug-in modules are inserted into the front side of a magazine equipped at its rear side with a rear wall circuit board. This circuit board accommodates female multipoint connectors with which the multipoint connectors of the plug-in modules mate. The female multipoint connectors are electrically interconnected by means of conductor paths on the rear wall circuit board.
Larger communications devices are composed of a plurality of such magazines which are electrically interconnected by means of cable harnesses. These cable harnesses are produced by high-cost manual labor in which errors may occur. Due to this manual labor, the positions of the individual wires in the cable harnesses differ from item to item. The result is that the electrical properties, particularly the crosstalk attenuation between two wires or pairs of wires is likewise different and not predictable from item to item. This limits the use of cable harnesses when communications signals at higher frequencies are involved.
In many devices, a very large number of connections are required between the individual magazines, with these connections originating in one magazine in a certain sequence but ending in another magazine in a completely different sequence.
FIG. 1 illustrates a general plan view of a three-stage switching matrix for a communications exchange system. Each stage is composed of 16 submatrixes. If the above-described assembly system is used to realize such a switching matrix, the submatrixes will be configured as plug-in modules and will be accommodated in magazines arranged according to stages. In the example of FIG. 1, there result 16 plug-in modules G1 to G16 per stage (magazine), each module containing one submatrix. Each submatrix is composed of 256 switching points KP.
The respective 16 submatrixes, i.e. the 16 plug-in modules G1 to G16 of each stage, are accommodated in a separate magazine; the submatrixes of the first stage in a first magazine M1, those of the second stage in a second magazine M2 and those of the third stage in a third magazine M3.
Each plug-in module has 16 input terminals E1 to E16 and 16 output terminals A1 to A16. Since these input and output terminals likewise are all brought out of their respective magazines, each magazine, i.e. each stage, has 256 input terminals and 256 output terminals. The 256 input terminals of the first stage are connected with 256 data sources (not shown) and the 256 output terminals of the third stage are connected with 256 data sinks (not shown). According to the scheme shown in Table 1 below, the 256 output terminals of the first stage are connected with the 256 input terminals of the second stage and the 256 output terminals of the second stage are connected with the 256 input terminals of the third stage.
______________________________________ First and second stage Second and third stage output input plug-in module terminals plug-in module terminals ______________________________________ G1 A1 G1 E1 A2 G2 E1 . . . . . . . . . A16 G16 E1 G2 A1 G1 E2 A2 G2 E2 . . . . . . . . . A16 G16 E2 etc. etc. to to G16 A1 G1 E16 A2 G2 E16 . . . . . . . . . A16 G16 E16 ______________________________________
Heretofore the connections between stages would be accomplished by manually assembled wiring harnesses, resulting in the problems previously described.